As the main target of R14, 3D Multi-Input Multi-Output (3D MIMO) enhancement mainly comprises improving the robustness of an actual deployment scenario, which at least shall include a high speed deployment scenario.
In a high speed scenario, it is generally recommended to use a larger measurement and report period, because a PMI with a short report period will cause a performance loss due to quick changes in channels. However, in this case, in view of measurement and feedback latency, Channel State Information (CSI) fed back by a user possibly fails to precisely reflect channel states. The CSI generally comprises information such as PMI, Channel Quality Indicator (CQI), Rank Indicator (RI) and the like. That is, the PMI fed back is possibly expired, which will cause a mismatched precoding strategy. Thus, it is desired to make it possible to provide a solution capable of adjusting the PMI fed back, so as to solve the problem of expiration of the PMI in the high speed scenario.